In a motor vehicle, the steering column serves firstly to transmit steering commands from the steering wheel which is fitted at the rear end of the steering shaft to the steering gear mechanism, generally with an auxiliary force being coupled to reinforce the manual steering torque introduced into the steering wheel. Furthermore, the cover unit which receives at the bodywork side the rotatable support of the steering shaft generally acts as a carrier for electrical switching and operating elements which can be manually activated during travel, such as, for example, indicator, headlight and windshield wiper switches. To this end, in most cases a plurality of switching and operating elements are combined in a steering shaft switch which is assembled as a modular subassembly on the cover unit.
In order to receive the steering column switch, there is constructed on the cover unit an interface which corresponds to securing devices on the steering column switch and which, for example, may have defined abutment faces, securing elements and the like for positionally correct fixing of the steering column switch to the steering column. The interface is preferably constructed in such a manner that the steering column switch can be assembled during production on the steering column which is already mounted in the vehicle.
In a generic steering column, the steering column switch is not only mechanically secured to the interface, but instead a rotational movement of the steering shaft is also transmitted to the steering column switch in order to actuate switching elements by means of a steering movement, for instance, a return device for independent return of the indicator switch after a turning maneuver. The transmission of the rotational movement is carried out by means of a transmission element which is coupled to the steering shaft in a rotationally secure manner and which has at least one actuation means which protrudes with respect to the steering shaft and which when the steering shaft is rotated cooperates with a corresponding switching element of the steering column switch which is fitted to the interface. For example, the actuation means may have an eccentric cam or journal which, in the event of a rotation of the steering shaft, moves a switching lever or trigger mechanism of the steering column switch.
In the prior art, for example, in DE 199 20 994 A1, a transmission element for a steering column is described. The transmission element which is described therein as a rotary connector has pin-like, axially protruding positive-locking elements which are connected in a positive-locking manner to a steering wheel which is itself secured in a rotationally secure manner to the steering shaft. Although a torque-conducting connection is thereby achieved with the steering shaft, it is disadvantageous that, as a result of the successive connections between the transmission element and steering wheel and between the steering wheel and steering shaft, a high level of complexity for complying with the predetermined tolerance requirements is produced.
From DE 720 718 a steering column is also known having a transmission element which is secured to the steering shaft so as to conduct torque. This transmission element is clamped to the steering shaft by way of a securing means, that is to say, by means of a clamping screw which is radially screwed into the transmission element. It is disadvantageous in this instance that the transmission element and the securing means have to be produced and assembled individually which requires a corresponding production and assembly complexity. Furthermore, the steering column which is disclosed therein has only one integrated electric switching contact and no interface for fitting a steering shaft switch. This arrangement is consequently unsuitable for use in modern motor vehicles.
Thus a need exists for a steering column for a motor vehicle that can be produced and assembled in a simpler and more cost-effective manner.